Q42850

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Q42850: Near Const Data Placed in _DATA in C 5.10

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Article: Q42850
Product(s): See article
Version(s): 5.00 5.10 | 5.10
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | | mspl13_c
Last Modified: 17-MAY-1989

Question:

I have a program which was originally written in Microsoft C Version
5.00. From the combined source-object code listing, I notice that the
near constant data items are placed in the _CONST segment of DGROUP.
In C Version 5.10, these same data items are placed in the _DATA
segment. Is there a reason for this, and can I specify the items to
remain in _CONST?

Response:

In C 5.00, near constant data was placed in _CONST because it was
constant and produced more easily ROMable code. Unfortunately, the /Gt
and /ND switches would not affect it. C Version 5.10 reverted to the C
Version 4.00 convention of putting such data in _DATA. The /Gm switch
is provided to specify the C Version 5.00 convention instead.

For more information see the Update section, Page 51, of the
"Microsoft C 5.10 Optimizing Compiler User's Guide."

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